Testing of Hypothesis: H2
6.2 Results
6.2.1 Effect of CCT on viewers’ perception for water-based paintings:
To understand the effect of CCT on water-based paintings 14 factors have been clustered under principal factors. Table 6.1 shows the result of factor loadings with total variance explained in parenthesis for water-based paintings. From the result, it can be seen that all the factors can be explained through three main factors. Factor
1 can be named as ‘pleasantness’ which represents the atmospheric perception of lighting to the viewers while viewing paintings. It includes factors such as relaxed, comfortable, pleasant, positive impact, soft, natural and high quality. Factor 2 can be named as ‘contrast’ that defines light effect on the colour of the paintings. It includes factors like high contrast, bright, colourful and clear. Factor 3 can be named as ‘warmth’ that provides information about the appearance of paintings to the viewers under certain lighting condition. It includes factors like warm, artistic and lively. Based on PCA result, ANOVA has been done to understand the effect of different CCTs on viewers’ perception. The result is summarized in table 6.2.
Table 6.1- Rotated Component Matrix of Factor analysis (water-based paintings) Factors Component
1(35.938%) 2(23.799%) 3(13.410%)
relaxed .865 .025 -.048
comfortable .828 .337 .164
pleasant .794 .441 .083
positive impact .793 .324 .134
soft .787 -.004 -.253
natural .778 .116 .347
high quality .571 .567 .263
high contrast -.080 .835 .198
bright .088 .772 .070
colourful .309 .732 .150
clear .371 .710 -.265
warm -.126 .097 .881
artistic .526 .057 .592
lively .500 .487 .553
Table 6.2- ANOVA result for effect of CCTs on viewers’ perception (water-based paintings)
Dependent Variable F- value p-value High contrast* 5.116 .008
Warm* 60.532 .000
Bright 2.770 .068
Clear* 4.717 .011
Colourful 1.277 .284
Natural* 5.128 .008
High quality* 9.661 .000 Positive impact* 7.217 .001
Relaxed 3.021 .054
Soft* 4.644 .012
Artistic* 6.152 .003
Lively* 11.606 .000
Comfortable* 5.245 .007
Pleasant* 5.213 .007
*indicates that the factor is statistically significant (p<0.05)
The ANOVA result (Table 6.2) shows that except three factors CCT has a statistically significant impact on all the factors. So, combining the results of factor analysis and ANOVA it can be said that CCT has a significant effect on the pleasantness of atmosphere, colour contrast of paintings and warmth feeling of viewers while viewing water-based paintings. Therefore, as hypothesized in H2, perception of viewers while viewing water-based paintings significantly changes due to different CCTs.
6.2.2 Preferred CCT by participants for water-based painting:
By comparing, the mean value of participants’ ratings (Table 6.3), it can be observed that participants have found out ‘pleasant’ atmosphere for viewing paintings under CW LED than under AD LED. Again, for colour contrast of paintings participants have found out CW LED having moderately contrast effect with the colour of paintings whereas, WW LED having extreme high contrast and AD LED having extreme low contrast. However, participants have rated the appearance of painting under AD LED as more clear compared to the other two. In case of ‘warmth’ feeling participants have rated CW LED in between extreme warm and extreme cool whereas, WW LED having extreme warmth feeling and AD LED having extreme cool feeling. Therefore, based on the discussion with the painters, it can be said that CW LED having moderately high contrast and warm feelings help to create a pleasurable display for water-based paintings.
Table 6.3- Mean value of participants’ ratings for water-based paintings
Factors Mean±SD
WW LED (CCT=2700K)
CW LED (CCT=3500K)
AD LED (CCT=6500K) High contrast 4.27±1.081 3.47±1.252 3.33±1.322
Warm 4.97±0.964 4.40±0.968 2.33±0.994
Clear 3.60±1.429 4.40±1.248 4.57±1.223
Natural 3.27±1.437 4.33±1.269 3.50±1.358 High quality 3.30±1.264 4.47±0.973 3.40±1.163 Positive impact 3.17±1.416 4.27±0.980 3.30±1.236
Soft 3.13±1.167 4.07±1.311 3.93±1.363
Artistic 3.33±1.348 4.47±1.137 4.17±1.392 Lively 3.73±1.437 4.60±1.133 3.07±1.112 Comfortable 3.60±1.354 4.67±1.155 3.87±1.456 Pleasant 3.53±1.224 4.53±1.196 3.97±1.189
To support and verify the result derived from this qualitative study, the gaze duration of viewers has been analyzed statistically. Fig.6.3 shows the plot of gaze data for water-based paintings. In the graph, X-axis represents different lamp CCTs and Y-axis represents the individual value of gaze data converted in fractional form.
From fig.6.3 it is evident that mean value of gaze duration for water-based painting under CW LED (CWLED=0.43, SD=0.069) is more than the mean value of gaze duration for water-based painting under WW LED (WWLED =0.23, SD=0.069) and AD LED (ADLED=0.33, SD=0.069). So, viewers have given more attention to
water-based painting exhibited under CW LED than the painting exhibited under WW LED and AD LED. It depicts that though the paintings were identical but viewers have perceived it differently due to the effect of different CCTs. Therefore, in accordance with the result derived from the qualitative study, this result also revealing that the perception of viewers while viewing water-based paintings changes due to different CCTs as hypothesized by H2.
Fig.6.3. Plot of gaze data for water-based paintings 6.2.3 Effect of CCT on viewers’ perception for oil-based paintings:
To understand the effect of CCTs on oil-based paintings similar statistical analysis method has been followed. Table 6.4 shows the result of factor loadings with total variance explained in parentheses for oil-based paintings. It can be seen from the table that among three principal factors, factor 1 explains 33.745% of variances, factor 2 explains 21.384% of variances and factor 3 explains 12.037% of variances.
So, none of the factors is ignorable. Again, factor 1, 2 and 3 can be named as
‘pleasantness’, ‘contrast’ and ‘warmth’ respectively. In this case, pleasantness consists of factors such as positive impact, comfortable, soft, natural, pleasant, high quality and relaxed. Contrast includes factors like bright, high contrast, colourful and clear. Warmth is defined by the factors warm and artistic. ANOVA has been done on extracted factors from PCA to verify the impact of CCTs on viewers’
perception while viewing oil-based paintings. The results are as shown in Table 6.5.
Table 6.4- Rotated Component Matrix of Factor analysis (oil-based paintings) Factors Component
1(33.745%) 2(21.384%) 3(12.037%) positive impact .821 .264 .062
comfortable .810 .223 .176
soft .798 .307 .009
natural .790 .041 .151
pleasant .751 .084 -.207
high quality .683 .196 .156
relaxed .673 -.024 .144
bright .074 .829 .019
high contrast -.015 .802 .114
colourful .282 .791 .274
clear .303 .712 -.038
lively .489 .493 .438
warm -.095 .158 .878
artistic .473 .044 .698
Table 6.5- ANOVA result for effect of CCTs on viewers’ perception (oil-based paintings)
Dependent Variable F-value p-value High contrast .376 .688
Warm* 38.739 .000
Bright 1.037 .359
Clear 1.942 .150
Colourful 1.247 .292
Natural* 6.529 .002
High quality* 15.071 .000 Positive impact* 8.887 .000
Relaxed 2.341 .102
Soft* 9.679 .000
Artistic* 6.245 .003
Lively* 3.482 .035
Comfortable* 9.056 .000 Pleasant* 9.830 .000
*indicates that the factor is statistically significant (p<0.05)
Table 6.5 shows that CCT has a significant impact on nine factors such as warm, natural, high quality, positive impact, soft, artistic, lively, comfortable and pleasant.
So, from the results, it can be said that pleasantness of viewers while viewing oil- based painting significantly changes due to different CCT. In sequence, the warmth feeling of viewers also significantly depends on lamp CCT. However, in the case of contrast, it can be seen that CCT is not statistically significant for viewing oil- based paintings. Therefore, from the angle of pleasantness and warmth feeling while viewing oil paintings it can be concluded that, the appearance of paintings changes due to different CCTs as hypothesized in H2.
6.2.4 Preferred CCT by participants for oil-based paintings:
By comparing the mean value rated by participants (Table 6.6) it can be observed that participants have found out ‘pleasant’ atmosphere for viewing paintings more under CW LED (CCT=3500K) than under AD LED (CCT=6500K) and WW LED(CCT=2700K). Again, for warmth feeling participants have rated CW LED in between extreme warm and extreme cool whereas, WW LED having extreme warmth feeling and AD LED having extreme cool feeling. Therefore, based on the discussion with the painters, it can be said that CW LED having moderately high contrast and little warm feelings help to create a pleasurable display for oil-based paintings as well as for water-based paintings.
Table 6.6- Mean value of participants’ ratings for oil-based paintings
Factors Mean±SD
WW LED (CCT=2700K)
CW LED (CCT=3500K)
AD LED (CCT=6500K)
Warm 5.17±0.791 4.43±0.971 2.87±1.279
Natural 3.37±1.299 4.47±1.074 3.47±1.502 High quality 3.17±1.177 4.60±0.894 3.57±1.040 Positive impact 3.47±1.306 4.80±1.064 4.00±1.313
Soft 3.40±1.248 4.67±1.061 4.10±1.029
Artistic 3.57±1.524 4.67±1.028 4.47±1.252 Lively 3.77±1.331 4.57±0.898 4.13±1.252 Comfortable 3.17±1.440 4.37±0.850 3.33±1.184 Pleasant 3.03±1.098 4.23±1.104 4.07±1.202
To support and verify the result derived from this qualitative study, the gaze duration of viewers has been analyzed statistically. Fig.6.4 shows the plot of gaze data for oil-based paintings. In the graph, X-axis represents different lamp CCTs and Y-axis represents the individual value of gaze data converted in fractional form.
Fig.6.4. Plot of gaze data for oil-based paintings
From fig.6.4 it is obvious that mean value of gaze duration for oil-based painting under CW LED (CWLED=0.36, SD=0.069) is more than the mean value of gaze duration for oil-based painting under WW LED (WWLED =0.32, SD=0.069) and AD LED (ADLED=0.33, SD=0.069). So, viewers have given more attention to oil painting exhibited under CW LED than the painting exhibited under WW LED and AD LED. It depicts that though the paintings were identical but viewers have perceived it differently due to the effect of lamp CCTs. Therefore, in accordance with the result derived from the qualitative study, this result also reveals that the perception of viewers while viewing oil-based paintings changes due to different CCTs as hypothesized by H2.
6.2.5 Effect of medium of paintings on viewers’ perception:
Based on both the experimental results associated with water-based and oil-based paintings it can be said that the effect of CCT on viewers’ perception while viewing paintings is similar irrespective of the medium of paintings. To verify this statement t-test has been done on common significant factors derived from the previous results (shown in table 6.2 and table 6.5). The result of this test is as shown in Table 6.7.
Table 6.7- t-test results for different medium of paintings Dependent Variable F-value p-value
Warm 0.697 0.405
Natural 0.389 0.534
High quality 0.268 0.606 Positive impact 0.127 0.722
Soft 2.696 0.102
Artistic 0.167 0.684
Lively 2.269 0.134
Comfortable 0.160 0.690
Pleasant 0.200 0.655
Table 6.7Table clearly shows that none of the factors is significantly changing (p>.05) with the variation of the medium of paintings. Therefore, it can be concluded that irrespective of the medium of paintings perception of viewers while viewing paintings changes due to the effect of CCTs.
6.3 Discussion:
The experimental results to verify H2 is suggesting that the perception of viewers depends on lamp CCT keeping other light parameters constant. Also, the result of this experimental study is revealing that the appearance of paintings is effected by the CCTs is valid irrespective of the medium of paintings considered in this present study. Therefore, it can be stated that H2 is applicable for any water and oil medium paintings. In succession, this experimental result depicts that CCT alone has a significant effect on the perception of pleasantness, which contradicts with previous studies [52] [53] [55]. Possibly, this contradiction has risen as because earlier studies are applicable for general room illumination, not for looking at any artwork. In succession, an earlier study on lighting condition for viewing painting concluded that viewer’s preference is negatively correlated
with CCT[60] can be partially agreed as because from this experimental result it has been seen that viewers have preferred CW LED over WW LED. Perhaps, similarity among the paintings has helped viewers to understand and differentiate the effect of CCT more precisely. Moreover, the difference in geographical factor leads to variation in colour preference[93] that may be applicable for preference of colour temperature of lamp also.
Fig. 6.5. Effect of CCTs on visual perception
Experimental result of this present study as summarized in fig.6.5 reveals that three principal factors, namely, pleasantness, contrast and warmth determining the effect of CCT on the appearance of water-based paintings and two principal factors, namely, pleasantness and warmth determining the effect of CCT on the appearance of oil-based paintings. By comparing the mean values of viewers’ preference, it has been observed that for both medium of paintings, in comparison to WW LED and AD LED, CW LED creates more pleasant appearance of paintings. Also, from the data of viewers’ gaze duration on paintings, it has been seen that participants have given more attention to paintings exhibited under CW LED than other two light sources. Therefore, in tune with earlier researchers [91], it can be concluded that CW LED with 3500K colour temperature has moderately warm effects on the appearance of paintings that lies in between cool and warm.
The results of this experimental study are suggesting that the art galleries of India need to consider CW LED as a prime source for lighting design to enrich viewers’ satisfaction. In succession which illumination level of CW LED is preferred by the viewers, need to be understood. In the next chapter, an experiment has been carried out to verify the effect of illumination levels on perception of viewers.
